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TMS320F280025: What if missing clock detection (MCD) is disabled?

Wayne Huang
Genius 16505 points
Part Number: TMS320F280025


Dear Champs,

I am asking this for our customer.

The user uses below code Line168 to disable missing clock detection.

And the user uses 20 MHz external crystal during run time.

Now, they found the 20 MHz external crystal worked well but it seemed in some rare case, the clock seemed to switch to 10 MHz.

They are clarifying this.

Therefore,

Questions:

1. If they disable MCD, can the hardware still switch from external crystal to INTOSC1 if the external crystal fails?

2. The user also enables in SYSREF Line 167 but disable MCD in 168, does it matter? That is, if PLL fails for some reason, does this MCD still works?

  • 0
    TI__Guru* 80820 points

    Wayne,

    The missing clock detection logic is responsible for generating the clock_fail signal inside the device.  This signal is what switches the clock to the INTOSC1, so if customer disables missing clock detect the device WILL NOT switch over if there is a clock failure.

    To the second question, enabling the PLL detect won't have an effect if the missing clock logic is disabled/off.

    Best,

    Matthew